Using intracellular recording techniques in an isolated perfused retina, the physiological properties of bipolar cells will be studied. Particular emphasis will be placed on identifying ionic mechanisms involved in generating post-synaptic potentials and, using additional techniques, such as the analysis of voltage noise in the bipolar cell, the characteristics of transmitter action at the post-synaptic membrane. In conjunction with data obtained from photo-receptors, in the same preparation important aspects of signal transfer, such as the synaptic gain and the temporal filtering of signals by the synapse, can be examined directly. A parallel E-M study of these synapses will be undertaken to seek structural correlates to their functional properties.